Global warming: Glacial runoff waning in Andes

SUMMIT COUNTY — South American glaciers that provide critical drinking water are retreating faster than expected, and meltwater discharge is also decreasing.

This means that the millions of people in the region who depend on the water for electricity, agriculture and drinking water could soon face serious problems because of reduced water supplies, according to a team of researchers who have closely monitoring the glaciers in the northern Andes.

The glaciers in Peru’s Cordillera Blanca are shrinking about 1 percent per year, and that percentage is increasing steadily, according to McGill University doctoral student Michel Baraer. They are currently shrinking by about one per cent a year, and that percentage is increasing steadily, according to his calculations.

“When a glacier starts to retreat, at some point you reach a plateau and from this point onwards, you have a decrease in the discharge of melt water from the glacier,” said Baraer.

As a result, the volume of water discharging from the glaciers into the Rio Santa in Northern Peru could drop by as much as 30 percent during the dry season.

“Where scientists once believed that they had 10 to 20 years to adapt to reduced runoff, that time is now up,” said Baraer. “For almost all the watersheds we have studied, we have good evidence that we have passed peak water.”